Aqueous alkaline metal halogenite compositions are well known for use in the textile industry wherein the halogenite, especially sodium chlorite, is a source of chlorine dioxide gas, a strong bleachant. Below about pH 9, there is a sufficient concentration of H.sup.+ ions to commence conversion of the chlorite ion to chlorine dioxide, especially at elevated temperatures. As the concentration of chlorine dioxide in the aqueous solution increases, aqueous alkali metal halogenite compositions become more acidic and the rate of conversion of sodium chlorite to chlorine dioxide increases.
French Patent No. 1,453,380 discloses alkali metal halogenite compositions, especially containing sodium chlorite, containing an alkali-medium-stable surface active agent having a saturated aliphatic chain and which is selected from among saturated compounds or arylaliphatic compounds having an aliphatic portion that is saturated or is very resistant to oxidation, condensed with an oxyethylene chain comprising at least 8 ethoxy groups, the terminal hydroxy group of which is esterified by a nonoxidizable acid. In particular, the French patent discloses as the stable surfactant alkali salts of the condensation product of a substituted phenol having a saturated aliphatic chain with an oxyethylene chain having at least 8 hydroxy groups, the terminal hydroxy group of which is esterified by an inorganic acid such as phosphoric acid or sulfuric acid, for example, the potassium salt of the phosphoric diester of phenol condensed with 10 molecules with ethylene oxide having the formula: ##STR1##
According to the French patent, salification of the terminal hydroxy group is indispensable in order to avoid oxidation of the surface-active agent in alkaline medium. Typically, the compositions of the French patent have an initial sodium chlorite concentration of about 14%.
U.S. Pat. No. 3,580,851 to Heid, et al., discloses sodium chlorite compositions containing a stable surface-active agent carboxylic acids or their alkaline salts having the general formula: ##STR2## wherein R is --C.sub.n H.sub.2n+1 or ##STR3## n denotes an integer of from 6 to 18, preferably 7 to 12; x is an integer of from 6 to 30, preferably from 9 to 19; y is 0 or 1, and R.sub.1 is hydrogen or metal. Particularly preferred ether carboxylic acids are the reaction products of ethoxylated alkyl phenols and ethoxylated alcohols with monochloroacetic acid and ether carboxylic acids obtained by the addition of acrylonitrile or methacrylonitrile to ethoxylated alkyl phenols or alcohols and subsequent saponification of the formed nitriles. Preferably, the weight ratio of sodium chlorite to surfactant ranges from 10:1 to 1:1.
In the paper industry, sodium chlorite has been used to prevent mold and growth in paper mill "white" water, as disclosed in U.S. Pat. No. 3,046,185 to Buonanno. Italian Patent No. 701,572 discloses an aqueous composition containing a mixture of sodium hypochlorite and sodium chlorite for use in the purification of water, especially surface water as found in streams, lakes, etc., as well as for use in laundering because of its sterilizing and bleaching effect.
Applicant has found that alkali metal halogenite solutions, especially sodium chlorite solutions, are suitable for use in household and janitorial cleaning chores, for example, cleaning of tiles, porcelain surfaces, and drains.
For such compositions, especially for compositions for household use, the inclusion of a perfume is preferred. The perfume provides a pleasing fragrance to the composition, and when used in connection with, for example, the cleaning of toilet bowls, would provide an air freshener utility.
It has been observed, however, that many perfumes, which are complex mixes of natural and synthetic oils having oxidizable substituent groups, are not stable in the alkali metal halogenite compositions. Instability of the perfume is manifest by the formation of chlorine dioxide as within the composition, by loss of perfume intensity, and lowering of composition pH. Concomitant with the formation of chlorine dioxide is the loss of the alkali metal halogenite. Moreover, the odor of chlorine dioxide is penetrating and unpleasant, and would tend to override the fragrance, especially after even partial depletion thereof.
It has been found that for many perfumes that are otherwise unstable in aqueous alkaline metal halogenite compositions, inclusion can be successfully achieved by stabilizing the system with an effective amount of an anionic surfactant.
Accordingly, it is an object of the present invention to provide an aqueous cleaning composition comprising an alkali metal halogenite solution containing therein a perfume that does not lose to an appreciable extent its characteristic fragrance.
It is a further and primary object of the present invention to provide such composition wherein the included perfume does not react appreciably with the alkali metal halogenite to release in excess of trace levels of chlorine dioxide gas, at the pH of the composition.
These and other objects and advantages of the present invention will be more readily understood upon reading the detailed disclosure of the invention, a summary of which follows.